Poly(arylene ether) resins have been blended with polyamide resins to provide compositions having a wide variety of beneficial properties such as heat resistance, chemical resistance, impact strength, hydrolytic stability and dimensional stability.
These beneficial properties are desirable in a wide variety of applications and the shapes and sizes of the parts required for these applications vary widely. As a result there are a variety of forming or molding methods employed such as injection molding, compression molding and extrusion. Each forming method requires a different set of physical characteristics for the polymer being formed. For example, materials that are preferable for use in high shear forming processes such as injection molding are usually designed to have relatively low melt viscosities (high melt volume rate (MVR)) at shear rates greater than 1000 s−1 in order to allow adequate mold cavity filling without excessive pressures. Alternatively, materials that are more preferred for use in low shear forming processes such as profile extrusion are usually designed to have relatively high melt viscosities (low MVR) at shear rates less than 1000 s−1. This is because profile extrusion requires that the material be forced through a shaped die (a profile) and maintain the extruded shape until cooled. The extruded shape can be further manipulated while the polymer blend is still warm through the use of shaping tools and the shaped profile must retain its shape after manipulation. A material with high melt viscosity is better able to maintain the shape until cooling is completed. A blend which is suitable for high shear processes such as injection molding may not be suitable for low shear processes such as blow molding, sheet extrusion and profile extrusion.
In some applications it is desirable that the extruded shape be electrostatically paintable which requires use of a conductive material. Unfortunately the inclusion of electrically conductive additives in high melt viscosity blends can be problematic, particularly in a multi phase polymer blends such as a poly(arylene ether)/polyamide blend.